Fix Chromium clang plugin warnings

webrtc/common.gyp

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 {
   'includes': ['build/common.gypi'],
   'targets': [
     {
       'target_name': 'webrtc_common',
       'type': 'static_library',
       'sources': [
         'audio_sink.h',
+        'common.cc',
+        'common.h',
         'common_types.cc',
         'common_types.h',
         'config.h',
         'config.cc',
         'engine_configurations.h',
         'typedefs.h',
       ],
     },
   ],
 }